carcinogenic

Carcinogenic is an adjective used to describe substances, agents, or exposures that have the potential to cause cancer. In practice, a carcinogen may be a chemical compound, a physical agent, a biological agent, or a lifestyle factor that can initiate or promote tumor development by damaging DNA or altering cellular processes.

Common examples include tobacco smoke, asbestos fibers, ultraviolet radiation from the sun or tanning beds, and ionizing radiation. Certain natural toxins such as aflatoxin B1 are also carcinogenic. Some viruses, notably human papillomavirus, are classified as carcinogenic because they can disrupt cellular regulation and promote malignant transformation. Carcinogenic risk depends on factors such as exposure level, duration, and individual susceptibility.

Carcinogens can act through different mechanisms. Genotoxic carcinogens damage DNA directly, causing mutations or DNA adducts. Others act as epigenetic modifiers, or as promoters that enhance the growth of initiated cells. The overall risk relates to dose, exposure timing, and the biological context of the exposed tissue.

Classification systems assess the strength of evidence linking a substance to cancer. The International Agency for Research on Cancer (IARC) uses groups: Group 1: carcinogenic to humans; Group 2A: probably carcinogenic to humans; Group 2B: possibly carcinogenic; Group 3: not classifiable; Group 4: probably not carcinogenic to humans. Not all exposures identified as carcinogenic cause cancer in every individual, but they contribute to increased risk under certain conditions.

Understanding and mitigating exposure to known carcinogens is a primary focus of public health and regulation.